Breeding ecology of the rainforest dung beetle Cephalodesmius armiger (Scarabaeidae) in Tooloom National Park

Abstract

The ecology of the rainforest dung beetle Cephalodesmius armiger was investigated in Tooloom National Park, within the high-altitude rainforest of north-east New South Wales. We observed considerable overlap in the brood-rearing stages of the breeding cycle. The operational sex ratio was female-biased. Biparental care is provided in this species, but it is not obligatory; females reared one brood either in partnership with a male or alone, and males did or did not pair with a female and rear a brood. There was spatial variation in the density of burrows. The availability of brood-burrows for brood rearing appears to be limited and evidence of the recycling of brood-burrows was collected for the first time. We suggest that the temporal variation in the breeding cycle arises from individual variation in the development and degeneration of the reproductive organs, rather than ecological factors favouring burrow and larder preparation. The female-biased operation sex ratio may result in males being more selective in their choice of mates than females and less committed to brood rearing.